Conventionally, there is known a printing device that employs an ink ribbon accommodated in a cassette to print characters and the like on a printing medium. It is necessary to ensure that the positioning of the cassette is stable when the cassette is mounted in the printing device in order for the printing device to perform reliable printing on the printing medium. As an example, Japanese Patent Application Publication No. 2006-56263 discloses a conventional printing device that includes a mounting section and a cover. The cassette is mounted in the mounting section. The cover is configured to cover the mounting section from above and can open and close thereon. First through fourth pressing members are disposed on the cover. When the cover is closed over the mounting section, the first through fourth pressing members press the cassette into the mounting section, thereby stabilizing the position of the cassette when the cassette is mounted in the printing device.